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GarrettCom 8000X User Manual

Page 17

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Magnum 8000X Mixed-Media Fiber Hubs Installation and User Guide (05/ 02)

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for factory configuration at time of order. It is also possible for the rear bonus port to be

re-configured in the field by a trained technician to add or exchange a Switching Port

Module. Figure 2.5a below shows the internals of the Magnum 8000X with an SPM

installed in the Bonus Port, accessible from the rear.

Figure 2.5a: Inside view of Magnum 8000X with SPM installed. (Rear view)

For the specifications of available Switch Port Modules (SPMs), see Section

1.3. The functions of an SPM are described below.

1. Filtering and Forwarding / Address Learning

The SPM has two ports - one where media attaches, and one connecting into

the inside of the mixed-media fiber hub in which the SPM is mounted. For each packet

received by either port of the SPM, a decision is made to either filter the packet or to

forward the packet to the other port. Error packets are always filtered. For good packets,

the filter or forward decision is made based on the destination address contained in each

packet. If the destination address is on the segment from which the packet originated,

then it is filtered and not forwarded to the other segment. If the destination address

didn’t find a match in the address table, then is it forwarded to the other segment. If it is

a new address which the SPM didn’t previously didn’t know about, it “learns” the new

address and puts it in the port’s address table. The address tables have a capacity of 1K

addresses for each port.

MAIN BOARD

SPM
MODULE

POWER
SUPPLY

FAN

STACKING
CONNECTORS